The best places to see sunflowers in Lopburi are in the districts of Phatthana Nikhom, Chai Badan, and Khok Samrong. This is where I headed at the weekend. From Bangkok, I took Highway 1 north through Saraburi and then turned off onto Road 21 a little while later. The sunflower fields are usually easy to find as you just have to follow the signs. However, this year due to the floods, there are not as many. Also, as you can see by these pictures, the sunflowers are not very big. I visited this same field three years ago and it was very crowded. When I went at the weekend, I was the only one there.